Comparison of computational predictions of material failure using nonlocal damage models

Abstract

In computational analysis of damage failure the strain delocalizations are of great importance in predicting assessment of structure integrity. In this paper we are investigating effects of the intrinsic material length on computational prediction of material failure using both cell model, i.e. the conventional micro-mechanical damage model with the constant–sized finite elements for the damage zones, and nonlocal damage model based on the gradient plasticity. The corresponding experiments performed for an engineering steel are taken as reference for verification. The experimental observation has revealed that reducing the specimen size will arise the specific strength of small notched specimen which cannot be predicted using the cell damage model. The nonlocal damage model based on the strain gradient-dependent constitutive plasticity theory reproduces the experimental records. The material length affects evolution of the material porosity and gives an understandable explanation of the size effect.